The goblet cells in a section of small intestine fail to show any blue staining with the Movat pentachrome stain. What could possibly be the result of?

• A. Treating the slides with alkaline alcohol too briefly
• B. Excessive dehydration
• C. Overstaining with eosin
• D. Incomplete deparaffinization

Answer: (A)

The key idea is that goblet cells are colored blue by the alcian blue component of Movat pentachrome, which stains acidic mucins in these cells. Alcian blue binds to the negatively charged mucopolysaccharides under acidic conditions, so the dye must be applied in the proper acidic environment and allowed to interact with the tissue for the right amount of time.

If the slide is treated with alkaline alcohol too briefly, the pH during the staining step is disrupted and the alcian blue cannot bind effectively to the mucins or may be washed out. This prevents the goblet cells from taking up the blue color, so they fail to stain blue.

Other issues listed—like incomplete deparaffinization, excessive dehydration, or overstaining with eosin—would either hinder stain penetration overall or affect other colors, but they don’t specifically explain the loss of blue in goblet cells the way an improper alkaline exposure during the alcian blue step does.